Re: machine performance!

["Howard Bailey" <bogmstr-at-infomagic.net>]

> hello all,
> I need some help in finding a literature about a proper ways to measure
cnc
> machines performance, I've been looking for some while without any
> luck....what I need is some kind of test procedures that is performed on
the
> cnc machine...(say milling machine) that tells you this machine is better
> than this...of course overriding the machine specifications that comes
from
> the manufacturer...
> that's why ...I like the idea of the web site that holds all the
information
> it's really a good one?
> hassan rabe
>

Hassan,

I don't have specific literature citations, but some tests are based on a
machine's thermal stability.  Run the machine for several hours until
everything comes to relatively steady state temperatures and finish bore a
hole of a given size.  Shut the machine down and let it cool for an hour and
bore another hole of the same diameter.  The closer the sizes of the two
holes, the better the thermal stability of the machine in this test.  I
would imagine that one stiffness test might be the feedrate at which a
machine can hold a given tolerance on a corner radius.  I don't know the
details, but "ball bar" tests are used to check circular interpolation
accuracy to a very high degree.

Regards,

Howard Bailey